1. Field of the Invention
The present invention relates to deep-well submersible pump and more particularly to ones in which a pump is lowered down a casing resting on sloping lake bottom to pump water to the shoreline.
2. Background
Systems using a submersible pump with a motor installed in a casing depend on the casing to contain the pump and motor. They also use a pipe installed in the casing to convey the fluid from the pump to the point of delivery. The motor torque is restrained by the pipe.
A mechanical wedging system is an alternative used to restrain the motor torque in the casing.
Current deep well installations also use shaft-driven submerged pumps with the motor placed above ground. These systems require the removal of the pipe and drive shaft to remove the pump for repair and servicing. The same difficulties associated with removal are experienced with installation.
An example of prior art deep well adapters with inflatable seal means is described in U.S. Pat. No. 2,843,052 to Andrus. The device described relies on a precharged gas chamber that is lowered into a well casing with an inflatable seal with heat actuated fusible plug valves to inflate and deflate this seal. Heat for fusion is an electrical element with the control switch at the top of the well. The Andrus device is more complex than our invention in that it has a submerged gas chamber and an inflatable bladder whereas our invention has only the inflatable bladder in the well to effect the seal and torsion restraint. Although our device has an air supply line that is not required on the Andrus device, it is less costly and has a major advantage. If the fusible plug fails to function to deflate the bladder there is no economical way to remove the pump system, especially in our preferred embodiment where the casing is on a slope and is not straight. Access to the head of the casing on lakeshore installations is often limited by steep terrain which also precludes the use of conventional pump retrieval equipment.
Furthermore, Andrus has no provision for installing his device in a sloped casing. Our device provides wheels. Also, the Andrus device cannot be relocated in the casing without complete removal from the well and recharging the gas chamber.
It is apparent from Andrus' diagram that the cylinder containing the inflatable tube and gas chamber casting could bind against the casing wall if said casing has dents or other surface irregularities. Dents and surface irregularities are common in lake casing installations.
Another weakness of the Andrus device is that deflation, according to the diagram, is by the gas escaping into the casing where the water pressure is equal to the pressure on the sealing tube. This would not allow a complete deflation and could cause removal problems.